MLA

Van Vechten, Carl, 1880-1964. Holiday, Billie. Box 92, folder 1617. 1949 March 23. https://collections.library.yale.edu/catalog/2001904.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 92, folder 1617"])(1949 March 23)[Holiday, Billie]. https://collections.library.yale.edu/catalog/2001904.